Devices to produce an air current have been in existence for many years, including fans, propellers, "squirrel cages" and the like. Some such devices are for specialized purposes. The present invention relates to the specialized purposes of drying carpet and conveying air through ducting to a desired location, such as in the case of introducing fresh air to a construction enclosure or other confined space.
Such devices in the prior art typically have been highly specialized, awkward and expensive. The configuration of carpet dryers in particular is limited by their mode of use. Soaked or flooded carpets are dried by pulling up one edge of the carpet off the carpet tack strip at the carpet edge adjacent a wall, and bending the carpet slightly away from the wall to produce a space between the wall and the carpet edge. The carpet drier is configured to direct an air flow through that space and under the carpet, that is, between the carpet and the floor. The carpet drier must therefore be of such a design that it can fit between the carpet edge and the wall, yet still be of sufficient size to house a substantial fan. Because the device will be positioned close to the wall, the air inlet should not be in a side where it will be blocked by the wall. The design constraints are generally satisfied with a housing in which the axis of rotation of the fan is vertical with an air inlet in the top of the housing. Air is drawn vertically through the fan, and is then directed horizontally out the bottom of the carpet blower by a vent in a shroud located beneath the fan housing. The bottom of the shroud rests on the floor to support the entire device.
In an alternative procedure, soaked or flooded carpets are dried by blowing air over the top of the carpet, rather than by raising a carpet edge and blowing air between the carpet and the floor as described in the preceding paragraph. This alternative procedure can be accomplished with the same carpet blower apparatus described in the preceding paragraph which is used for blowing air between the carpet and the floor. The carpet drier is simply placed adjacent a wall with the shroud vent directed horizontally across the room to blow air over the top of the carpet. It can be appreciated that under either drying procedure the drier should be configured with the fan axis of rotation vertical; with the shroud vent such that air is directed horizontal; with appropriate shroud internal surfaces to translate the vertical air flow from the fan into a horizontal air flow to exit the vent; and with a minimum dimension between the vent side of the shroud and the opposite side of the shroud in order to allow placement of the vent close to the wall where the device can serve to dry areas of the carpet that are close to the wall as well as areas farther away from the wall.
Carpet driers of the "squirrel cage" type generally have a housing with an inlet at the back or on the side and a wide outlet at the front. There are several significant drawbacks to such a design. The inlet positioned low on the housing results in the uptake of moist air off the wet carpet rather than drier air from well above the carpet. Moist air is of course much less effective than drier air in drying the carpet. Because the entire housing is disposed close to the floor, the motor and other electrical components are positioned on or near the soaked carpet where they are subject to corrosion.
Air blowers are also commonly used for supplying fresh air to construction enclosures or other confined spaces. Such enclosures and spaces include tents or other temporary structures used as shelters in the service of utility boxes or to cover manholes that access water and sewer facilities or to cover excavations. Tents in particular have become increasingly popular as temporary shelters for such purposes, due to their low cost, light weight, durability and, especially with recent technological advances, very fast installation time. Such tents require a constant supply of fresh air due to their small interior volume. In the case of water and sewer facilities, a constant supply of fresh air is required due to both the small interior volume of the working space and the noxious fumes that are often present.
Air blowers are often combined with ducting for these purposes. The ducting is a length of flexible tubular-shaped fabric or plastic which is supported by a semi-rigid metal or plastic element spirally wound through the ducting. The support provides sufficient rigidity to keep the interior of ducting open to allow unrestricted air passage. The ducting can be collapsed in the axial direction for storage by reducing the spacing between spirally wound supports to thereby fold the flexible fabric or plastic wall between the spiral windings. A duct having an extended length of 20 to 30 feet can thus be collapsed for storage into a length of only 2 to 3 feet. The collapsing and extension of the duct requires little effort; the collapsing is accomplished by simply pushing the ends together and the extension is accomplished by simply pulling the ends apart. The collapsed duct may be stored in a hollow cylindrical duct housing which protects it from damage, prevents it from accidentally extending, and allows for easy transport and storage.
Like carpet driers, air blowers with ducting tend to be bulky and expensive. There is therefore a need for air blowing devices which are less bulky and expensive and which preferably use interchangeable elements to allow for multiple uses.